Brake shoe adjusting means



S. SCHNELL BRAKE SHOE ADJUSTING MEANS Jul 31, 1945.

Filed July 26, 1943 2 Sheets-Sheet l r INVENTOR.

. S.SCHNELL ATTORNEY July 31, 1945.- s. SCHNELL v BRAKE SHOE ADJUSTING MEANS Filed July 26, 1943 m m m. wx o t, [mm .b I \\M2 81%,. .N 7 2 3 m n F lNVENTOR HNELL ATTORNE Patented July 31, 1945 S PATENT OFFICE BRAKE SHOE ADJUSTING MEANS Steve Schnell, Kirkwood, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application July 26, 1943, Serial- No. 496,118

17 Claims.

perature.

Another object of my invention is to provide an improved brake shoe adjusting means which can be set to give an initial 011 position clearance for the shoe when installed and will function throughout the life of the shoe lining to maintain such clearance under all conditions.

ed on the backing plate by means ofa pin ii. This pin is provided with an eccentric portion H on which the arm is journaled and the pin is clamped to the backing plate by means of a nut l3. The inner end of the pin extends through an opening It in the web of the brake shoe and carries washers i cooperating with the opposite sides of the web for guiding and steadying the Yet, another object of my invention is to provide an adjusting means for a brake shoe which will function to make an adjustment when the drum expands due to increasing'temperature and will also make adjustments as the drum again assumes its normal condition to thus maintain a predetermined ofi" position clearance for the shoe at all times.

Other objects of my invention will become 'apparent from the following description taken in connection with the accompanying drawings in which Figure l is a view of part of a brake assembly having a shoe adjusting means embodying my invention; Figure 2 is an enlarged view showing the different parts of the adjusting mechanism: and Figures 3, 4, and 5 are sectional views taken on the lines 3-3, 1-4, and 5--5, respectively, of Figure 1.

Referring to the drawings in detail, numeral ll indicates a brake drum secured to rotate with the wheel of the vehicle and 2 a fixed backing plate or support Zor closing the open side of the drum. A brake shoe 3 is provided for cooperation with the drum, said shoe having its lower or heel end pivotally mounted on the backing plate by means of an anchor pin t and being actuated at its toe end by a' fluid motor 5 secured to the backing plate. The fluid motor is actuated by fluid under pressure from a remote source as is well-known practice. The brake shoe comprises a web 6 and a lining carrying flange l to which is secured the lining 8 for cooperation with the drum surface. The brake shoe is retracted from the drum by a retracting spring 9 which is connected between the brake shoe 3 and the companion brake shoe (not shown) of the brake assembly.

The brake shoe adjusting mechanism embodying my invention has an arm l0 pivotally mountsurface at all times.

shoe. By loosening the nut to, pin H can be rotated to change the pivotal axis of arm it).

Also mounted on the backing plate is an L- shaped lever l6 pivoted at the juncture of its arms I'll and ill by means of a pin i9 carried by the backing plate. The arm 08 of the lever has a lateral extending portion ill on its end to extend beneath the end of arm Hi. This end of arm in has a cam'surface it with whichthe extension 20 cooperates. The cam surface ii is between two shoulders 22 and 23 which cooperate with extension 2i! to limit the rotative movement of arm it]. When engaging with cam surface 2!, extension 20 prevents any counter-clockwise rotation of lever it about its pivot i9. Thus arm I! of the lever can act as a stop to determine the "off position of the brake shoe and in order to perform this function, the brake shoe carries a pin 24 which can engage the end of arm ll of lever l6. Lever it and arm it have interposed between them a coil spring 25 which acts to move arm ill with respect to lever it and adjust cam surface 20 with respect to extension 2]]. When arm ill is caused to be moved relatively about its pivotal axis in a counter-clockwise direction relative to lever it, cam surface it will adjust lever it and cause the upper end of arm ll of said lever to be moved in a direction toward the shoe, thus making an adjustment of the off position of the brake shoe. If arm it should be moved in a clockwise direction relatively to lever it, arm ll of said lever will be moved in a direction away from the shoe, thus making an adjustment of the off" position of the shoe.

The brake shoe lining carrying flange l and web 6 are cut away to provide for the mountin of an adjusting plunger 26 which has a slot 21 for receiving the web of the shoe (see Figure 4). The shoe lining also has an opening coinciding with the opening in the lining carrying flange of the shoe and carried by the plunger 2% in a plug 28 of friction material projectingthrough the lining opening in order to contact with the drum Plunger 26 engages with the central portion of. arm it and controls the movement oi. said arm. The plunger and the friction plug are so arranged that when the plug is flush with the suriace of the lining. the plunger will engage-the web at the bottom of its slot 21. When the shoe is retracted from the drum-and pin 24 engages arm II of lever I, the web of the= shoe will be spaced from the bottom of slot 21 a distancewhich will be equal to that of the ofl" position clearance desired for the shoe.

Referring to the operation of the adjusting thatarm ilofleverlewillbemovedin mechanism, arm II and lever it are first pivotally mounted. on the backing plate and then plunger 20 mounted on the shoe in the cut away portion of the lining carrying flange and the web.

In making the original adjustment the plunger is pushed inwardly so that the bottom of its slot 21 engages the web of the shoe and then the material of plug II is ground so thatit isi'iush with the surface of the brake lining. Nextthe adjustable pin ii is adjusted so that arm it forces I plunger is outwardly and the end surface of the plug extends beyond the lining surface the 'distance desired for the "o position clearance of the shoe with respectto the'drum. When'this adjustment is completed, nothingels'e-need' be 7 done throughout the entire life of thebrahe lining adjustments thereafter will take place aulmnatically..

I When the brake shoe is released mm the pin 24 will engage the end of armjll'which is held from movement by the engagement of ei- 1 tension It with surface 2|. The friction engage- "ment between extension II and the 'cam-surface 2|, together with spring ilfwill. hold-arm 1's in its position ,where the plug 28 of the plunger,

engages with the drum. When the brake shoe is applied to the drum, plunger II and plug II will not be moved relatively to the surface of the thedrumsurface with the same pressureaslthe lining If there is wear, there will also be a like amount of wear of the material of the plug. ConsequentLv. as the lining carrying flange of the steadily increases. when there is no shoe moves closer to the drum due to li'ning wear,

the plunger will be moved slightly away from arm l0 and this will permit spring 2' to become eifective and cause arm ill to follow the plunger. Since pin 2| on the shoe does not engage arm ll when the brake shoe is applied, there will be no heavy friction between cam surface Ii and extension 20 and the movement of the arm can take place freely. With the new setting of camsurface II, the upper end of arm II will be moved in a direction toward the shoe to establish a new "off" position for the shoe. The cam surface 2| isso arrangedwithrespecttothepivotaiaxisof arm ili that for each increment of lining wear there will be such a movement of arm l0 as to cause the end ofarm ll of the lever to be moved in a direction toward the shoe the same increment.

If, during brake shoe application, there should be an expansion ofthe drum due to increased temperature, an adjustment will take place in the same manner as when the lining wears since the plunger will move suiiiciently to cause a following movement of arm ll. When the shoe is released, the "oil" position clearance of the lining with respect to the drum will not be'altered. After an adjustment caused by heating is made and there are no more brake shoe applications,

slightly in a clockwise direction.

stage, shoulder as is so arranged that thedrumwillcoolandcontract. Whenoontrsctlonoccurathsdrumsurface 20 inwardly and came arm thecamsurfacewithrespecttoexiensionl m emeritus-contractions:

gardless of what occurs, the brake shoe, released fromthedrum, will always have determined with respect to the When the adjusting is originally theoperatoris notreqmred'todoany lusting throushout the entire meet the When the brake lining ap a it gage extension "and cause adjusting opera to cease. 'niis'wiil be a warning to thatthe liningisaboutworn'out aware that. more movement is required move his brake shoes into engagement with. drum as the "off"; position clearance automa adjustment. He can then have his brake relined. The material of the plug is preferably made of slightly harder material than the liningsincethedrumrubsonitwhenthe are released. The rubbing, however,

n the high spots ofthe drum surface, jAny'il-r- T111801 thebrakewhen the shoeis'dis'engsged the lliltment' from the drum will not affect Under released condition of the brake shoe it is tobenoted thatthe strong retractingsprlngis pulling on the brake shoe and, consequently. also actsonlever liduetothearmthereofbeingengaged by pin ll. With this pull on lever ",extension" onarm l'loftheleverisheldfirmly against the cam surface Ii, thus preventing any movement of arm i0. Spring 15 also aids in maintaining the adjustment since its force acts to place a slight pressure on'the plunger and maintain the plug thereof in light contact with the drum. A

Being awareof the possibility of modifications in theparticul'arstruouireherein described without departing from the fundamental principles of my invention, I do not intend that its scope belimited exceptassetforthbytheappended claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a brake shoe adjusting mechanism; a sup. port; a brake drum rotatable with respect to said support; a brake shoe having a friction element thereon movable into operative and inoperative association with said "drum; a second friction element movable relatively to said shoe and brake shoe; and means on said support for associating said member, said shoe and said second friction-element for so moving said member when there is wear on the friction surface of said second friction element or when said shoe has movement relative to the support that the disengaged clearance of the friction element on the shoe with respect to the drum will remain constant.

2. In adjusting mechanism, a support, two friction elements one of which is movable to engage with and be disengaged from the other and said other element having movement with respect to the support resulting from the engagement of the two elements, a member associated with the support and cooperating with the engaging and. disengaging movable element for determining the clearance between the elements when disengaged, and means for so automatically moving the member when said other element has movement relative to the support that the disengaged clearance of the elements will remain constant, said last named means comprising a control element car'- ried by the movable element and ,in constant contact with said other element, said movable element having relative movement with respect to the control element throughout the entire engaging and disengaging movement of said movable element.

3. In an adjusting mechanism for a brake; a support; a, drum rotatable with respect thereto; a first friction element selectively engageable with said drum; a second friction element movable with respect to said first friction element and in constant engagement'with said drum; a lever pivotally mounted on the support and havin a part cooperating with one of said friction elements for determining the clearance between said first friction element and said drum; and means for moving said lever relatively to said support and said friction elements to maintain the disengaged clearance constant between one of said elements and said drum.

4. In an adjusting mechanism for a brake to maintain a constant clearance between a brake shoe and a brake drum; a support; a brake drum rotatable with respect to said support; a brake shoe pivotally mounted on said support for selective engagement with said drum; a friction element transversely movable with respect to said shoe and in constant engagement with said drum;

c said friction element governing the clearance between said drum and said shoe; cooperating means between said shoe and said support; cooperating means between said friction element and said shoe; and means coordinating said two cooperating means such that a movement in said shoe or in said frictionelement will adjust the other to govern the clearance between said shoe and said drum.

5. In adjusting mechanism for a brake, a support, a drum, a brake shoe for engagement with and disengagement from the drum, a member pivotally mounted on the support and engageable by a shoe part when disengaged from the drum, and means movable transversely of said shoe inengagement with said drum for automatically moving said member about its pivot relative to said shoe and drum so that the clearance between the shoe and the drum when the shoe is disengaged will be substantially constant regardless of wear of the shoe friction surface or change in diameter of the drum.

6. In adjusting mechanism for a brake, a support, a brake drum, a brakeshoe for engagement with and disengagement from the drum, a mem-' ber pivotally mounted on the support and engage able by a shoe partwhen disengaged'from the drum, and means for automatically moving said member. about its pivot, said last named means comprising an element carried by the shoe andv in constant engagement with the drum.

7. In adjusting mechanism for a brake, a support, a brake drum, a brake shoe for engagement with and disengagement from the drum,a member pivotally mounted on the support and engageable by a shoe part when disengaged from the drum, and means for automatically moving said member about its pivot and in a direction toward the shoe when there is wear of the friction-surface of the shoe, said means comprising an element in constant contact with the drum and so mounted on the shoe that the shoe will move relatively thereto during its engaging and disengaging movement and said element will be caused to wear and move with the shoe as the friction surface of said shoe wears.

- 8. In adjusting mechanism for a brake, a support, a brake drum, a brake shoe for engagement with and disengagement from the drum, a member associated with the support and engageable by a part of the shoe when disengaged from the drum, and means for automatically moving said member so that the clearance between the shoe and the drum when the shoe is disengaged will be maintained constant regardless of drum expansion or contraction due to changes in temperature, said last named means comprising an element mounted on the support and an element carried by the shoe and in constant engagement with the drum for changing the position of said member as the drum expands and contracts.

9. In adjusting mechanism for a brake, a support, a brake drum, a brake shoe for engagement with and disengagement from the drum, a member associated with th support and engageable by a part of the shoe when disengaged from the drum, and means for automatically moving said member so that the clearance between the shoe and the drum when the shoe is disengaged will be maintained constant regardless of drum expansion or contraction due to changes in temperature, said last named means comprising a control element carried by the shoe and in constant engagement with the drum, said shoe having relative movement with respect to the control element throughout the entire engaging and disengaging movement thereof.

10. In adjusting mechanism for a brake, a support, a drum, abrake shoe'mounted on the support, a lever pivoted on the support and having a part spaced from its pivot for engagement by a part of the shoe when retracted, an arm pivoted on the support, means carried by the lever and arm for preventingmovement of the lever when engaged by the shoe and thereby determine the off position of the shoe, said last named means also being so arranged that movement of the arm relatively to the lever will permit change of position of the lever to change the off position of the shoe, and means for moving the arm in accordance with wear of the friction surface of the shoe.

11. In adjusting mechanism for a brake, a support, a drum, a brake shoe mounted on the sup port, a lever pivoted on the support and having a part spaced from its pivot for engagement by a part of the shoe, an arm pivoted on the support, said arm and lever being so associated that the arm will prevent movement of the lever hen engaged by the shoe and thereby determine the "off" position of the shoe, cam means on the arm controlled by a movement of the arm relatively to the lever to permit change of position of the lever and the "011 position of the shoe, and means for moving the arm when there is wear of the friction surface of the shoe or change in the diameter of the drum.

12. In adjusting mechanism for a brake, a support, a drum, a brake shoe mounted on the support, a lever pivoted on the support and having a part spaced from its pivot for engagement by a part of the shoe, an arm pivoted on the support, said arm and lever being so associated that the arm will prevent movement of the lever when engaged by the shoe and thereby determine the off position of the shoe, cam means on the arm controlled by a movement of the arm relatively to the lever to permit change of position of the lever and the "off" position of the shoe, and means comprising an element carried by the shoe and in constant contact with the drum for controlling movement of the arm in accordance with any change in the diameter of the drum.

13. In adjusting mechanism for a brake, a support, a drum, a brake shoe mounted on the support, an L-shaped lever pivoted on the support and having one arm adapted to be engaged by a part of the shoe to determine the "off position clearance of the shoe, an arm pivoted on the support and cooperating with the other arm of the lever for preventing movement of the lever when engaged by the shoe, said arm being provided with a cam surfacewith which said last named arm of the lever cooperates for controlling the positioning of the lever when the arm is moved about its pivot, and means for controlling the movement of the arm in accordance with wear of the friction surface of the shoe or change in diameter of the drum.

14. In adjusting mechanism for a brake, a support, adrum, a brake shoe mounted on the support, an L-shaped lever pivoted on the support and having one arm adapted to be engaged by a part of the shoe to determine the off" position clearance of the shoe, an arm pivoted on the support and cooperating with the arm of the other lever for preventing movement of the lever when engaged by the shoe, said arm being provided with a cam surface with which said last named arm of the lever cooperates for controlling the positioning of the lever when the arm is moved about its pivot, an element carried by the shoe and engaged by the arm, spring means acting on the arm and biasing the element into constant contact with the drum, and cooperating means between the element and the shoe for causing the element to move with the shoe after the shoe has-engaged the drum.

15. In adjusting mechanism for a brake, a support, a brake drum, a brake shoe mounted on the support, a retracting spring for the shoe, a lever pivoted on the support and having a part engaged by a part of the brake shoe when retracted from the drum, a movable member mounted on the support and cooperating with another part of the lever for preventing movement of the lever when engaged by the shoe and for changing the position of thelever to change the disengaged position of the shoe, and means extending transversely of said shoe in constant engagement with said drum for causing movement of the member when there is brake shoe friction surface wear or change in diameter of the drum. 7

16. In adjusting mechanism for a brake, a support, a brake drum, a brake shoe mounted on the support, a retracting spring for the shoe, a lever pivoted on the support and having a part engaged by a part of the brake shoe when retracted from the drum, a movable member mounted on the support and cooperating with another part of the lever for preventing movement of the lever when engaged by the shoe and for changing the position of the lever to change the disengaged position of the shoe, and means for causing movement of the member when there is brake shoe friction surface wear or change in diameter of the drum, said last named means comprising an element, carried by the shoe cooperating with the-movable member and constantly contacting the drum.

17. In a brake adjusting mechanism, a support, a brake drum in operative relation thereto, a pair of friction elements transversely movable relatively to each other and to said drum to engaged and disengaged positions, one of said elements selectively engageable with said drum and the other continuously engageable with said drum, a member mounted on said support having a portion movable relatively to said drum and substantially radially of one of said friction elements to determine the disengaged clearance of one of said friction elements relative to said drum, and means for moving said member relative to said support and one of said friction elements in the event of wear on said friction element to keep said disengaged clearance constant.

STEVE SCI-INELL. 

